Wildlife and Endangered Species

Threatened and endangered species occur in many parts of the California ground squirrels' range. It is important to be properly informed about the presence of these species before carrying out any management program.​Using the California Department of Pesticide Regulation's PRESCRIBE database will help you identify the range of many endangered species. PRESCRIBE also describes limitations on bait application per active ingredient or product.​

Secondary Toxicity to Wildlife

​The use of rodenticides, particularly anticoagulant rodenticides, may involve the risk of secondary toxicity, i.e. the death (mortality) of a nontarget animal after it consumes a rodent that has ingested toxic bait. It is important to be aware of the risks involved in toxic baiting of California ground squirrels so that harm to wildlife can be prevented.

The risk of secondary toxicity varies among toxic baits. There are two types of toxic baits available for the management of California ground squirrels: 1) products containing first-generation anticoagulants (FGARs) and 2) the acute toxicant, zinc phosphide.

FGAR use for ground squirrel management should have limited secondary toxicity risk to nontarget species as long as products are applied per label instructions and all necessary measures are followed prior to, during, and after bait application.​The use of second-generation anticoagulants is not permitted in California ground squirrel management. Compared to FGAR-associated risks, secondary toxicity risks are significantly greater when using second-generation anticoagulant rodenticides. This is because second-generation anticoagulants tend to accumulate and persist in the liver and kidneys for a much longer period of time. There is essentially no secondary toxicity risk associated with the application of zinc phosphide. Unlike anticoagulant rodenticides, the toxicant does not persist in any tissues after death.​

Limiting Bait Exposure to Non-Target Species

Numerous precautions can be taken to mitigate risks to endangered species when using toxic baits. In addition to protecting wildlife, these safeguards help to make ground squirrel management programs as efficient and effective as possible.

Bait Acceptance TrialsBait acceptance trials are often required by product labels before toxic baits can be applied. These trials enable you to see if ground squirrels are actively accepting the bait carrier. If bait acceptance is low or nonexistent, then another management option should be considered. This is especially true in the ranges of endangered species, which may consume the bait that the ground squirrels do not eat. If endangered species are seen consuming nontoxic grains during bait acceptance trials, other measures must be implemented to prevent them from accessing these toxic baits.

​Modified "T" Bait StationModified "T" bait stations can also be used to mitigate toxic bait risks to threatened and endangered species. As with elevated bait stations, the bait station entrance should be at least 12 inches above the ground. Clear away vegetation surrounding the trap.

Elevated Bait StationsThe use of elevated bait stations will prevent several species from accessing toxic bait, most notably threatened and endangered species of kangaroo rats. Use these guidelines to make elevated bait stations as inaccessible to nontarget wildlife as possible:

The platform of the bait station should be raised at least 12 inches above the ground.

Do not use a solid base. Rest the platform on legs inset at least 2 inches from the edge of the platform to keep kangaroo rats from climbing into the station.

Vegetation should be cleared from around the bait station.

Secure the bait station to the platform to prevent it from being tipped over by other animals. In rangeland or in other areas where livestock are present, it may be necessary to secure the entire platform and station to the ground to prevent livestock from tipping it over.

Avoid spilling bait. It may be necessary to add a lip to the top of the platform to stop grain spillage. Any grain spilled from bait stations should be picked-up daily.

In kit fox range, the entrance to the station should be no greater than 3 inches in diameter.